MCQ – 84308

Correct Answer � C Explanation

Answer- C- The intensity of radiation is inversely proportional to the square of distance from the source

The correct answer is C. The intensity of radiation is inversely proportional to the square of the distance from the source.

This statement is a fundamental principle of radiation physics known as the inverse square law. It states that the intensity of radiation decreases in proportion to the square of the distance from the source of radiation. Essentially, if you double the distance from the radiation source, the intensity of radiation falls to a quarter of its original value. This principle is crucial for planning and administering radiotherapy to ensure that the correct dose is delivered to the cancer cells while minimizing exposure to surrounding healthy tissues.

To address the other options:

A. Rapidly dividing cells are resistant to radiation: This is incorrect. Rapidly dividing cells, including many types of cancer cells, are generally more sensitive to radiation, not resistant. This is because radiation more effectively damages cells that are in the process of dividing.

B. GI mucosa is one of the most radioresistant tissues in the body: This is incorrect. The gastrointestinal (GI) mucosa is actually one of the most radiosensitive tissues. The cells in the GI tract divide rapidly, making them more vulnerable to radiation damage.

D. Small blood vessels are least resistant to radiation: This is also incorrect. Small blood vessels can be quite sensitive to radiation. Radiation can damage the endothelial cells lining the vessels, leading to radiation-induced vasculitis and other complications.

So, the true statement about radiosensitivity of tissues is the one regarding the inverse square law of radiation.